Biology Lecture: Alternative Splicing

Introduction to Splicing

Splicing: A post-transcriptional process where introns are removed and exons are joined.
- Introns: Non-coding regions, also known as intervening sequences.
- Exons: Coding regions, referred to as expressed sequences.
In eukaryotic cells, pre-mRNA is transcribed and undergoes splicing to form mature mRNA.

Alternative Splicing: A regulated process allowing multiple protein isoforms to originate from a single pre-mRNA transcript.
- Involves exons or introns being differentially joined or skipped.
- Results in different combinations of exons that lead to multiple protein isoforms from a single gene.

mRNA transcripts are subjected to different splicing patterns, resulting in different protein structures.
Differential Splicing: Exons can be joined or skipped in various ways, leading to diverse protein structures and functions.
Different isoforms can carry out different cellular functions despite originating from the same gene.

In humans, 95% of multi-exon genes undergo alternative splicing.
Alternative splicing significantly enhances the diversity of proteins encoded by the genome.
It explains how a small number of genes can lead to a vast array of proteins in humans.

Highly regulated process involving:
- Regulatory Sequences: In mRNA, introns may play regulatory roles rather than being simply degraded.
- Proteins Involved:
  - Activator Proteins: Enhance certain splicing actions.
  - Repressor Proteins: Inhibit certain splicing actions.
Spliceosome: A large complex of RNA and protein essential for executing the splicing process.
- Works in coordination with activator and repressor proteins to precisely cut and join mRNA.

Alternative splicing is crucial for protein diversity and gene expression regulation.
Additional learning resources are available on related topics like post-transcriptional modifications, including capping, poly-A tailing, etc.